1. Field of the Invention
The present invention relates to a lens-fitted photographic film unit, and more particularly to a photographic film unit in which parts that are disassembled are given distinguishing characteristics upon disassembly so as to prevent errors during reassembly.
2. The Known Prior Art
Lens-fitted photographic film units (hereinafter referred to as film units) are now on the market, e.g. under a trade name "Quick Snap" (manufactured by Fuji Photo Film Co., Ltd.), which are a single-use camera pre-loaded with photographic film. These film units make it possible to take pictures whenever desired without buying or carrying an expensive and heavy camera, and can take pictures of suitable quality at low cost.
A user who has purchased the film unit winds up the film frame by frame for each exposure. The film unit in its entirety is forwarded to a photo laboratory after the whole strip of the film is exposed. An operator at the laboratory unloads the exposed film from the film unit and subjects it to development and printing in accordance with conventional photographic processing techniques. The user receives photoprints and a negative film but does not receive the film housing of the film unit.
The film housing after processing has heretofore been destroyed and discarded as waste with consequent pollution of the environment, so that it is desirable to recycle the film housing after processing. There could be two ways of recycling the film housing: to reassemble reusable parts as withdrawn, and to remold and regenerate moldable parts.
To recycle film units, film housings as emptied of film by a photofinisher are sent to and disassembled by a manufacturer. Parts to be disengaged from the film unit are provided with hooks and holes adapted for easy disengagement by deformation of the hooks. The parts as withdrawn are inspected and reassembled and the reassembled unit is loaded with new, unexposed film. Such easy disassembly enables parts to be recycled at little expense. Reassembly enables manufacture of film units at less cost too.
However, there is a problem in the reuse of parts of film units, in that the parts as withdrawn are often somewhat damaged or worn after one or more times of being disassembled. The film comes into direct contact with a main body and a rear cover: the main body has an exposure aperture for forming a frame on the film and has a film roll chamber for containing a roll of the film; the rear cover has a film contact surface for pressing the film against the exposure aperture, in the manner of a pressure plate. When any of the exposure aperture, the roll chamber, and the film contact surface is scratched, contact with the scratched portion causes scratches on the film, and will degrade the quality of photoprints that will be made from the exposed film. It is therefore desirable, in recycling, not to reuse, but rather to regenerate such synthetic resin parts as the rear cover, by subjecting them to melting and remolding, in which they are melted to resin pellets and then remolded.
The all-resin parts as disassembled, however, include a front cover and the rear cover: the former can be reused as it is, but the latter must be regenerated before it can be reassembled. To reassemble film units requires steps of classification and handling different resin parts separately. Furthermore, the rear cover as disassembled tends to be indistinguishable from newly molded ones. If the used rear cover as disassembled should be accidentally mixed in with remolded rear covers, the used rear cover would be hardly discernible from unused rear covers and so as a practical matter would not be removed from the reassembling process.